For the following processes, state whether each of the thermodynamic quantities q, w, delta U, and delta H is greater than, equal to, or less than zero for the system described. Explain your answers briefly. Note: adiabatic means no heat flow, isothermal means constant temperature. a. An ideal gas expands adiabatically against an external pressure of 1 bar.
b. An ideal gas expands isothermally against an external pressure of 1 bar.
c. An ideal gas expands adiabatically into a vacuum.
d. A liquid at its boiling point is converted reversibly into its vapor, at constant temperature and 1 bar pressure.
e. H2 gas and O2 gas react in a closed container at 25 degrees Celsius and the product water is brought back to 25 degrees Celsius.

its b it was a compound

answer: - first one is the correct answer. .

explanations: - potassium sulfide is and cobalt(ii) chloride is .

charge on k is +1, charge on s is -2, charge on co is +2 and charge on cl is -1.

in a double replacement reaction the ion exchange takes place. in general the reaction looks like:

if one of the product is insoluble as per solubility rules then a precipitate of it is formed.

when we mix the aqueous solutions of potassium sulfide and cobalt(ii) chloride then chloride ion goes with potassium ion and sulfide ion goes with cobalt ion and the balanced equation is written as:

k and cl has equal charges, similarly co and s has equal charges and hence no subscripts are used for the product side.

as per the solubility rules, cos is insoluble and so it's precipitate is formed.

looking at the given choices, first choice is correct.